Prime Minister Julia Gillard says Labor will bring the federal budget back into surplus in 2012/13 but the opposition cannot make that commitment.
Opposition Leader Tony Abbott said a coalition government would get the budget back to surplus "as quickly as possible".
Ms Gillard is more certain 2012/13 will be a surplus year.
"Today, I can say on behalf of the government we are determined to deliver a budget surplus in 2012/13 and we will," she told reporters in Canberra.
"Mr Abbott on his words today endorsed the words of his finance minister which would mean they would not commit to a budget surplus in the next five years."
Finance spokesman Andrew Robb said on Tuesday the coalition would have to consider the government's books when it got into office before it would be in a position to say when the first surplus would be delivered.
Opposition treasury spokesman Joe Hockey later on Tuesday said the coalition could achieve a surplus in 2012/13, based on current information.
